fix infer

tests/ocr_det_params.txt

@@ -3,7 +3,7 @@ model_name:ocr_det
 python:python3.7
 gpu_list:0|0,1
 Global.use_gpu:True|True
-Global.auto_cast:False
+Global.auto_cast:null
 Global.epoch_num:lite_train_infer=2|whole_train_infer=300
 Global.save_model_dir:./output/
 Train.loader.batch_size_per_card:lite_train_infer=2|whole_train_infer=4
@@ -34,16 +34,16 @@ distill_export:null
 export1:null
 export2:null
 ##
-infer_model:./inference/ch_ppocr_mobile_v2.0_det_train/best_accuracy|./inference/ch_mobile_det_quant_dev_lr/
-infer_export:tools/export_model.py -c configs/det/det_mv3_db.yml -o |null
-infer_quant:False|True
+infer_model:./inference/ch_ppocr_mobile_v2.0_det_infer/
+infer_export:null
+infer_quant:False
 inference:tools/infer/predict_det.py
---use_gpu:True
+--use_gpu:True|False
 --enable_mkldnn:True|False
 --cpu_threads:1|6
 --rec_batch_num:1
 --use_tensorrt:False|True
---precision:fp32|int8
+--precision:fp32|fp16|int8
 --det_model_dir:
 --image_dir:./inference/ch_det_data_50/all-sum-510/
 --save_log_path:null